One type of conventional securement device comprises, in its simplest form, a first plate constituting a lower gripping member fixed directly on the post head, and a second plate constituting an upper gripping member, each gripping member being provided with two parallel grooves disposed facing parallel grooves provided on the opposed gripping member. The facing grooves receive two rails constituted by metallic rods fixed on the lower surface of the saddle.
The upper gripping member is connected to the head of the saddle post by a gripping screw which passes through a bore provided in the saddle post head and through a bore provided in the lower gripping member. This gripping screw screws either into a tapped bore provided on the lower surface of the upper gripping member, or else into a nut on the upper surface of the upper gripping member, and in this latter case, it passes through a bore in the latter to coact with the nut.
However, even if this securement device permits a certain adjustment of the position of the saddle of about 20 mm in the longitudinal direction by movement of the device along rail sections which are parallel to each other, it does not permit an inclination of the saddle because the lower gripping member is fixed permanently on the post head and cannot be inclined.
So as to be able to regulate the inclination of the saddle, one solution consists in providing on the saddle post head an incurved surface, which is to say convex or concave, which contacts with the surface of complementary shape on the lower surface of the lower gripping member which is in this case constituted by a separate and detachable piece.
In another simplified securement device, the lower and upper gripping members are in the form of two halves of a tube cut along its length and comprising at its ends impressions corresponding to the shape of the saddle securement rails. These two half tubes are disposed facing each other and trapped by a circular slotted gripping collar and a gripping screw gripping the collar.
It is to be noted that all these securement devices determine a fixed longitudinal position for the gripping members, which limits the longitudinal adjustment of the saddle to the rectilinear and parallel paths of the portions of the saddle rails which can slide between the gripping members when these latter are ungripped.
Finally, there is another conventional saddle securement device permitting covering a wider range of adjustment as to length. This device comprises a slider movable in the longitudinal direction along a prismatic slide way formed on the head of the saddle post.
This slider has an upper concave surface coacting with a complementary surface on the lower surface of a plate with two parallel grooves constituting a lower gripping member.
The post head comprises on its lower surface a recess which serves to receive the head of a gripping screw which extends through one of three spaced bores opening on the upper surface of the slider to pass through, in this order, a bore provided in the slider, a slot provided in the lower gripping member, and a slot provided in a plate constituting a second gripping member with two parallel grooves so as finally to coact with a nut.
This nut has a lower convex cylindrical surface with a transverse axis received in a cylindrical concave recess of complementary shape which is provided on the upper surface of the upper gripping member. Thus, the gripping screw remains vertical whilst the inclination of the saddle can be adjusted. The adjustment of the position of the saddle takes place on the one hand as usual by letting the rails below the saddle slide in grooves of the lower and upper gripping members, and on the other hand by inserting the screw into one or the other of the three bores in the post head which represent a retracted position, a medial position and an advanced position.
One of the drawbacks of this device is that it is difficult during assembly to hold the nut such that its bore will be disposed vertically to receive the end of the gripping screw. In practice, in order to emplace the gripping screw, it is necessary to turn the gripping member more than 90° relative to its use position and then to return it by 90° such that the grooves of the upper and lower gripping members will be parallel to each other. This assembly is rendered still more difficult when the screw is located in the advance position near the saddle post.
Generally speaking, the assembly of all the known devices is more or less difficult when the saddle is in place, because on the one hand the access is then prevented from above and the available space below is very restricted because of the presence of the rails and of the post.
In the case in which moreover the screw is inclined forwardly, the approach of the gripping key to it is rendered more difficult because of the risk of interference with the saddle post. Avoiding this risk requires carrying out a very great and advanced excavation on the lower surface of the post head, which lowers the strength, increases the lateral size and as the case may be renders molding of the post more complex.